[821] | 1 | /* vi: set sw=4 ts=4: */
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| 2 | /*
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| 3 | * Mini umount implementation for busybox
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| 4 | *
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| 5 | * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
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| 6 | * Copyright (C) 2005 by Rob Landley <rob@landley.net>
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| 7 | *
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| 8 | * This program is licensed under the GNU General Public license (GPL)
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| 9 | * version 2 or later, see http://www.fsf.org/licensing/licenses/gpl.html
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| 10 | * or the file "LICENSE" in the busybox source tarball for the full text.
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| 11 | *
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| 12 | */
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| 13 |
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| 14 | #include "busybox.h"
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| 15 | #include <mntent.h>
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| 16 | #include <errno.h>
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| 17 | #include <getopt.h>
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| 18 |
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[904] | 19 | #define OPTION_STRING "flDnravd"
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[821] | 20 | #define OPT_FORCE 1
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| 21 | #define OPT_LAZY 2
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| 22 | #define OPT_DONTFREELOOP 4
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| 23 | #define OPT_NO_MTAB 8
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| 24 | #define OPT_REMOUNT 16
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[904] | 25 | #define OPT_ALL (ENABLE_FEATURE_UMOUNT_ALL ? 32 : 0)
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[821] | 26 |
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| 27 | int umount_main(int argc, char **argv)
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| 28 | {
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| 29 | int doForce;
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| 30 | char path[2*PATH_MAX];
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| 31 | struct mntent me;
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| 32 | FILE *fp;
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| 33 | int status = EXIT_SUCCESS;
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| 34 | unsigned long opt;
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| 35 | struct mtab_list {
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| 36 | char *dir;
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| 37 | char *device;
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| 38 | struct mtab_list *next;
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| 39 | } *mtl, *m;
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| 40 |
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| 41 | /* Parse any options */
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| 42 |
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| 43 | opt = bb_getopt_ulflags(argc, argv, OPTION_STRING);
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| 44 |
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| 45 | argc -= optind;
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| 46 | argv += optind;
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| 47 |
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| 48 | doForce = MAX((opt & OPT_FORCE), (opt & OPT_LAZY));
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| 49 |
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| 50 | /* Get a list of mount points from mtab. We read them all in now mostly
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| 51 | * for umount -a (so we don't have to worry about the list changing while
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| 52 | * we iterate over it, or about getting stuck in a loop on the same failing
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| 53 | * entry. Notice that this also naturally reverses the list so that -a
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| 54 | * umounts the most recent entries first. */
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| 55 |
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| 56 | m = mtl = 0;
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| 57 |
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| 58 | /* If we're umounting all, then m points to the start of the list and
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| 59 | * the argument list should be empty (which will match all). */
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| 60 |
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| 61 | if (!(fp = setmntent(bb_path_mtab_file, "r"))) {
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| 62 | if (opt & OPT_ALL)
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| 63 | bb_error_msg_and_die("Cannot open %s", bb_path_mtab_file);
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| 64 | } else while (getmntent_r(fp,&me,path,sizeof(path))) {
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| 65 | m = xmalloc(sizeof(struct mtab_list));
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| 66 | m->next = mtl;
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| 67 | m->device = bb_xstrdup(me.mnt_fsname);
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| 68 | m->dir = bb_xstrdup(me.mnt_dir);
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| 69 | mtl = m;
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| 70 | }
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| 71 | endmntent(fp);
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| 72 |
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| 73 | /* If we're not mounting all, we need at least one argument. */
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| 74 | if (!(opt & OPT_ALL)) {
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| 75 | m = 0;
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| 76 | if (!argc) bb_show_usage();
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| 77 | }
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| 78 |
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| 79 | // Loop through everything we're supposed to umount, and do so.
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| 80 | for (;;) {
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| 81 | int curstat;
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[904] | 82 | char *zapit = *argv;
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[821] | 83 |
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| 84 | // Do we already know what to umount this time through the loop?
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| 85 | if (m) safe_strncpy(path, m->dir, PATH_MAX);
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| 86 | // For umount -a, end of mtab means time to exit.
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| 87 | else if (opt & OPT_ALL) break;
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| 88 | // Get next command line argument (and look it up in mtab list)
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| 89 | else if (!argc--) break;
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| 90 | else {
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[904] | 91 | argv++;
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| 92 | realpath(zapit, path);
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[821] | 93 | for (m = mtl; m; m = m->next)
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| 94 | if (!strcmp(path, m->dir) || !strcmp(path, m->device))
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| 95 | break;
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| 96 | }
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[904] | 97 | // If we couldn't find this sucker in /etc/mtab, punt by passing our
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| 98 | // command line argument straight to the umount syscall. Otherwise,
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| 99 | // umount the directory even if we were given the block device.
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| 100 | if (m) zapit = m->dir;
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[821] | 101 |
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| 102 | // Let's ask the thing nicely to unmount.
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[904] | 103 | curstat = umount(zapit);
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[821] | 104 |
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| 105 | // Force the unmount, if necessary.
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| 106 | if (curstat && doForce) {
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[904] | 107 | curstat = umount2(zapit, doForce);
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[821] | 108 | if (curstat)
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[904] | 109 | bb_error_msg_and_die("forced umount of %s failed!", zapit);
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[821] | 110 | }
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| 111 |
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| 112 | // If still can't umount, maybe remount read-only?
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| 113 | if (curstat && (opt & OPT_REMOUNT) && errno == EBUSY && m) {
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[904] | 114 | curstat = mount(m->device, zapit, NULL, MS_REMOUNT|MS_RDONLY, NULL);
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[821] | 115 | bb_error_msg(curstat ? "Cannot remount %s read-only" :
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| 116 | "%s busy - remounted read-only", m->device);
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| 117 | }
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| 118 |
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| 119 | if (curstat) {
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[904] | 120 | status = EXIT_FAILURE;
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| 121 | bb_perror_msg("Couldn't umount %s", zapit);
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| 122 | } else {
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| 123 | /* De-allocate the loop device. This ioctl should be ignored on
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| 124 | * any non-loop block devices. */
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| 125 | if (ENABLE_FEATURE_MOUNT_LOOP && !(opt & OPT_DONTFREELOOP) && m)
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| 126 | del_loop(m->device);
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| 127 | if (ENABLE_FEATURE_MTAB_SUPPORT && !(opt & OPT_NO_MTAB) && m)
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[821] | 128 | erase_mtab(m->dir);
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| 129 | }
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[904] | 130 |
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[821] | 131 | // Find next matching mtab entry for -a or umount /dev
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[904] | 132 | // Note this means that "umount /dev/blah" will unmount all instances
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| 133 | // of /dev/blah, not just the most recent.
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[821] | 134 | while (m && (m = m->next))
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| 135 | if ((opt & OPT_ALL) || !strcmp(path,m->device))
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| 136 | break;
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| 137 | }
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| 138 |
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| 139 | // Free mtab list if necessary
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| 140 |
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| 141 | if (ENABLE_FEATURE_CLEAN_UP) {
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| 142 | while (mtl) {
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| 143 | m = mtl->next;
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| 144 | free(mtl->device);
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| 145 | free(mtl->dir);
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| 146 | free(mtl);
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| 147 | mtl=m;
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| 148 | }
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| 149 | }
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| 150 |
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| 151 | return status;
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| 152 | }
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